Existing software for CNC filament winding of fibre reinforced plastics has been linked to typical finite element codes by automating the generation of finite element models of filament wound components. The algorithms required for this process have been created and encoded as computer programs. The program FILFEM I generates models of components manufactured using the CADFIL I CAD/CAM system for the filament winding of axisymmetric components. The suite of programs named FILFEM II achieves the same objective for non-axisymmetric components manufactured using CADFIL II although its method of operation is quite different from that of FILFEM I. FILFEM I has been tested by automatically generating models of a pinched cylindrical filament-wound tube manufactured from glass-reinforced polyester resin. The results from these models generally compared well with results obtained from experiments and from an analytical solution extended by the author from work by Calladine. However, the validity of a comparison with experiment depends upon the accuracy of the material properties assumed in the analyses. The material property values required for the analyses were investigated experimentally. Tests based upon pinched rings and a modified split-disc method are described together with more conventional tests of material properties. A method is presented for the determination of unidirectional material properties from the experimentally-measured properties of laminates. Difficulties in obtaining consistent results were attributed to problems with the quality of the specimens, inadequacies in the orthotropic model of material behaviour, and to material damage occurring during the experiments. In order to provide a test component for FILFEM II, a number of filament wound elbows were manufactured although some problems with winding quality remain. The fibre paths files used in manufacturing the elbows were used to test the operation of FILFEM II and further work including experimental verification is proposed.

Polycarbonate-carbon nanotube nanocomposites are promising materials for electrostatic shielding and conductive packaging applications. The nanotubes impart electrical conductivity and increases thermal conductivity and stiffness of the matrix. However, the nanofiller also affects the rheology, and hence the evolution of a filler network during processing. This thesis examines the effects of matrix molar mass and of compounding temperature on the thermal, rheological, electrical and mechanical properties of these materials. Thermal analysis demonstrated that the glass transition decreased as a consequence of the nanotubes. Degradation of the matrix was ruled out as a possible cause, and the decrease was attributed to a poor interface between matrix and filler. Thermal conductivity of the matrix increased with the addition of nanotubes, in line with model predictions. Furthermore, the nanofillers also marginally increased thermal stability of the matrix in atmospheric conditions. Oscillatory shear rheology showed that the nanocomposites deviate from linearity earlier than the matrix polymers. A technique was developed to assemble mastercurves over an extended frequency range. The nanocomposites exhibit a low frequency plateau at ∼10^5 Pa, identified as the stiffness of the nanotube network. Relaxation times estimated from the peak in loss tangent scale with matrix molar mass in the same way as terminal relaxation times in pure matrix materials, providing evidence that relaxation of the polymer network is the dominant relaxation mechanism in filled and unfilled polymers. The effects of melt processing on electrical and mechanical properties were investigated using nanocomposites melt-compounded at a range of extrusion temperatures, but subsequently produced by either injection moulding or compression moulding. Electrical resistivity measurements obtained using a two-terminal method revealed that the resistivity of compression moulded specimens was an order of magnitude lower than that of injection moulded specimens. The compounding temperature had only a mild effect on resistivity. Compression moulded specimens also exhibited greater surface hardness and lower modulus than injection moulded specimens. The elastic modulus recorded is in line with expectation due to nanotube orientation, demonstrated using a modified Halpin-Tsai model. The model can explain much of the observed effects, but suggests that nanotubes may be considerably shortened by melt processing.

The state-of-the-art in dimensional metrology in terms of accuracy and 3D measurement is the micro-co-ordinate measuring machine, or micro-CMM. Current manufacturing trends are inclined towards miniaturisation, and all developments in this area are dependent on the capabilities of dimensional metrologists. Currently, the main limiting factor in the advancement of co-ordinate metrology at the micrometre scale is the design, manufacture and resulting accuracy of contacting micro-CMM probes. With this in mind, this thesis describes the development of a novel 3D vibrating micro-CMM probe. The main contributions of this thesis are as follows. Firstly, the current state of contact probing at the micrometre scale is reviewed and a clear set of knowledge gaps are identied for developments in this area. Secondly, the concept of a novel 3D vibrating micro-CMM probe is introduced as the background knowledge for this thesis. The mechanical and electrical properties of this vibrating micro-probe are modelled, as well as its intended operation. The operational model of the vibrating microprobe focusses on the surface interaction forces that are prevalent when probing at the micrometre scale. Thirdly, the operation of the vibrating micro-probe is validated experimentally. Initially, the ability of the vibrating micro-probe to counteract the surface interaction forces is investigated. Other areas of validation are in the determination of the probing point repeatability, the linearity error, and isotropy of the probe. Finally, the intended operation of the probe is compared to current national and international specication standards and guidelines for the operation of CMM probes. This work is directly aimed at ensuring that the developed vibrating micro-probe is capable of operating in an industrial or commercial metrology environment. A detailed set of operating strategies are also developed for ecient use of the vibrating micro-probe. It is concluded that the developed vibrating micro-probe will be able to address the current needs of the micro-CMM community. It is also concluded that the vibrating micro-probe has the ability to operate in a non-contact mode, further increasing its usefulness.

This thesis explores the use of cotton derived cellulose nanowhiskers (CNWs) in composite materials in the form of nanocomposite films, surface modified polymer fibres and also in self-reinforced (SR) composites. Cellulose nanowhiskers (CNWs) were produced from cotton via sulphuric acid hydrolysis process and blended with polylactic acid (PLA) to produce CNW-PLA and was added to hydroxyethyl cellulose (HEC) to manufacture CNW-HEC nanocomposite films. The aggregated morphology and hydrophilicity of CNWs, hydrophobicity of PLA and the solvent used (Chloroform) played a major role in creation of voids within the CNW-PLA nanocomposites. In addition, the aggregated morphology of the CNWs also influenced the surface roughness and light transparency properties of the CNW-HEC films. Improvement in the mechanical, thermal and thermomechanical properties for both types of nanocomposites was achieved due to the reinforcing effect of the rod-like nanowhiskers. An increase in the crystallinity of the nanocomposites indicated that the CNWs induced crystallisation in the matrices. Incorporation of CNWs also had a significant influence on accelerating the degradation profile of the CNW-PLA nanocomposites and reducing the swelling capacity and initial swelling rate for the CNW-HEC films. PLA fibres were also produced with varying diameters (11 µm to 38 µm) via a melt drawing process employing increasing take-up velocities. A higher degree of chain orientation as well as an increase in crystallinity for the thinner fibres was achieved due to strain-induced crystallisation. The variation in PLA fibre diameter also revealed a noticeable influence in their mechanical and moisture absorption properties at various humidity levels. Further, the hydrophobic and smooth surface of the PLA fibres was coated with various blends of CNWs (65 to 95 wt%) and polyvinyl acetate (PVAc) to impart roughness, where PVAc acted as a binder. An increase in tensile modulus and moisture absorption properties were achieved for the CNW/PVAc coated PLA fibres. These surface modified PLA fibres were aligned to produce unidirectional (UD) fibre mats prior to hot compaction (at 95oC) to manufacture SR PLA composites. Incorporation of CNW/PVAc within the SR PLA composites revealed an increase in their flexural and ductile properties compared to the control composite.

Structural Hollow Sections have superior structural performance over open sections and are currently available as circular, elliptical or rectangular sections. However, the practical use of these sections is limited due to complexities involved in their connections. The lack of access to the interior of the section makes it almost impossible to use standard bolted connections. The so-called Blind Bolts are therefore used as fasteners to alleviate these complexities by allowing for bolted rather than, the-not-so-popular, welded connections to hollow sections. Lindapter’s Hollo-Bolt is one of the Blind Bolts used for hollow sections connections. However its established use is currently restricted to transferring tensile forces and vertical shear only. Filling Square Hollow Sections (SHS) with concrete, when utilising Hollo-Bolts, was found to improve the connections’ performance in resisting moments, but there is currently no guidance available for the design of such connections. Many methods are used to model connections behaviour. The so-called component method has emerged to be the most favourite and has been adopted in the Eurocode 3. In this method, the connection is divided into basic components. Each component has a contribution to the structural behaviour of the connection. For Hollo-Bolted moment resisting connections, the behaviour of two of the components, fastener in tension and concrete-filled SHS face in bending, are not available. The application of the component method is therefore not possible. This research aims to devise a model to predict the behaviour of the concrete-filled SHS face in bending. A novel analytical model of the concrete-filled SHS face bending has been proposed in this work. The model has three parts: Initial Stiffness, Yield Force and Post-Yield Stiffness. The Initial Stiffness was formulated by theoretically substituting the face of the concrete-filled SHS with a beam element. The beam is assumed to be loaded by a rigid strip and fixed at its ends. Yield line analysis was used to investigate possible failure mechanisms and associated strengths. The model adopted the mechanism which theoretically led to the critical yield force. The Post-Yield Stiffness was taken as a percentage of the Initial Stiffness in line with other work from the literature. An extensive full-scale experimental programme was undertaken to calibrate the aforementioned analytical model, and to examine the effects of varying parameters on the SHS face bending behaviour. Typical experiments involved one row of two bolts pulled out of concrete-filled SHS. A special dummy bolts were manufactured to the exact size and geometry of open Hollo-Bolts, and were used in the experimental programme to remove the influence of any deformation associated with the real Hollo-Bolts, and thus isolate the face bending behaviour. Non-contact video-based equipment was used to record the SHS face deformation. Three parameters were varied: the SHS face slenderness ratio, the bolts gauge to SHS width ratio and the concrete in-fill compressive strength. A finite element model was also developed to complement the experimental programme. The model was developed using the ANSYS Parametric Design Language (APDL) to allow for easy parametric analysis and knowledge transfer. Dimensions, parameters and materials properties could be easily altered in the fully parametric model script. The outcomes of the experimental programme and the finite element model were used to formulate design charts for two calibration factors: kis for the calculation of Initial Stiffness, kyf for the calculation of Yield Force. A chart was also formulated for the Post-Yield stiffness ratio. The proposed analytical model (semi-analytical after calibration) was compared with the results of experimental programme and finite element modelling. The model was found to capture the behaviour of concrete-filled SHS face bending with sufficient accuracy, lying between 90% prediction lines derived from the experimental results. This is considered sufficient for the proposed model to capture the concrete-filled SHS face bending component for connection design purposes.

There is an increasing global demand to extend the life span of down-hole drilling tools in order to improve operation effectiveness and efficiency of oil and gas production. Laser cladding of tungsten carbide/Ni-based alloy metal matrix composite (MMC) coatings is currently being utilised for this purpose. However, the effect of tungsten carbide dissolution on the corrosion performance of the MMC coatings has not been completely understood. In this work, a study was carried out in which laser cladding of a stainless steel substrate using (i) Inconel 625 wire and (ii) tungsten carbide powder (Spherotene)/Inconel 625 wire was undertaken. This work was performed using a fibre laser system and has examined the process characteristics, the microstructure and the corrosion performance of the clad layers. Process characteristics studies were carried out by visual observation of the cladding process within a process window (laser power: 1-1.8 kW, traverse speed: 100-300 mm min-1, wire feed rate: 400-1000 mm min-1, powder feed rate: 25 g min-1). The microstructures were investigated using a combination of optical microscopy, scanning electron microscopy (with energy dispersive X-ray analysis) and X-ray diffraction. The volume fraction of tungsten carbide retained in the composite coatings was determined using image processing software. Corrosion performance was assessed using electrochemical corrosion testing in de-aerated 3.5 wt.% NaCl solution. Well bonded, minimally diluted, pore- and crack-free Inconel 625 wire and Spherotene (WC/W2C) powder/Inconel 625 wire composite coatings were successfully deposited. Cladding process characteristics were categorised into wire dripping, smooth wire deposition and wire stubbing within the range of parameters used in this work. Process maps which predict the characteristic of Inconel 625 wire and Spherotene (WC/W2C)/Inconel 625 wire fibre laser cladding at varying cladding conditions within the process window were developed. The volume fraction of tungsten carbide (WC/W2C) retained in the composite coatings was found to decrease with increasing laser power, traverse speed and wire feed rate. Tungsten carbide dissolution was found to result in the precipitation of intermetallic compounds including M6C and M23C6 in the γ-Ni matrix, which is rich in W and C. The increase in tungsten carbide dissolution was also found to increase the propensity for corrosion in the MMC coatings compared to the Inconel 625 wire coatings. As a result, the corrosion performance of the tungsten carbide/Ni based alloy MMC coatings can be improved by reducing the level of tungsten carbide dissolution through process control.

Modern electromagnetic problems are becoming increasingly complex and their simulation must take into account geometrical features that are both large and small compared to the wavelength of interest. These multi-scale problems lead to a heavy computational burden in a discretised computational simulation approach since the small features require fine mesh to be used in the simulation, resulting in large run time and memory storage. To overcome such problems, this thesis presents an efficient and versatile method for embedding small features into an otherwise coarse mesh. The embedded model eliminates the need for discretising the small features and allows for a relative large mesh size to be used, thus saving the computational costs. The subject of the thesis is embedding a thin film as a small feature into the numerical Transmission Line Modelling (TLM) method, although any small feature with known analytical response can be implemented in practice. In the embedded model, the thin film is treated as a section of transmission line, whose admittance matrix is used to describe the frequency response of the thin film. The admittance matrix is manipulated by expanding the constituent cotangent and cosecant functions analytically, and then transforming them from the frequency domain to the time domain using the inverse Z transform and general digital filter theory. In this way the frequency responses of the thin film are successfully embedded into the TLM algorithm. The embedded thin film model can be applied to both single and multiple thin film layers. The embedded thin film model has been implemented in the one-dimensional (1D) and two-dimensional (2D) TLM method in the thesis. In the 1D TLM method, the embedded thin film model is used to investigate the reflection and transmission properties of lossy,anisotropic and lossless thin films, e.g. carbon fibre composite (CFC) panels, titanium panels, antireflection (AR) coatings and fibre Bragg gratings (FBG). The shielding performance of CFC panels is also discussed. In the 2D TLM method, the embedded thin film model is extended to model arbitrary excitations and curved thin films. The electromagnetic behaviour of infinitely long CFC panels with oblique incidence and a CFC panel of finite length with a point source excitation are studied using the embedded thin film model. The resonant effects of CFC circular and elliptical resonators and the shielding performance of a CFC airfoil with the profile of NACA2415 are investigated using the embedded curved thin film model. In addition, the effects of small gaps in the airfoil structure on the shielding performance are also reported. All the examples discussed in the thesis have validated the accuracy, stability, convergence and efficiency of the embedded thin film model developed. At the same time, the embedded thin film model has been proven to have the advantage of significantly saving computational overheads.

Nowadays, numerical modelling is increasingly used to assess the stability of tunnels and underground caverns. However, an analysis of the mechanical behaviour of existing brick-lined tunnels remains challenging due to the complex material components. One promising approach is to carry out a series of small-scale physical tunnel model tests representing the true behaviour of a prototype under extreme loading in order to validate and develop the corresponding numerical models. A physical model test is advisable before any field study, which might be dangerous and costly. During the tests, advanced monitoring techniques such as the laser scanning and photogrammetry would be used to register tunnel deformation and lining defects. This investigation will show how these may substitute or supplement the conventional manual procedures. Simultaneously, numerical models will be developed, primarily using FLAC and UDEC software, to simulate the physical models after comparing their results. In this way, numerical simulations of physical models would be achieved and verified. These numerical models could then be applied to the field study in the future research, enabling accurate prediction of the actual mechanical behaviour of a masonry tunnel, in combination with advanced monitoring techniques.

Electrical discharge machining (EDM) is a manufacturing process capable of machining electrically conductive materials regardless of their mechanical properties. It finds extensive usage across the aerospace, automotive, medical implant and mould/die industries, and is particularly useful for the micro-machining of precision components with complicated shapes. The surface integrity of materials machined by EDM is typically poor, and reduced service life is often expected as a result of surface properties. For example, reduced fatigue performance can result due to the presence of surface cracks as well as porosity, high surface roughness and tensile residual stress. Increased surface area due to surface cracks, porosity and surface asperities also inhibits corrosion performance. This thesis explores from a fundamental perspective the damage and contamination occurring in the surfaces of materials machined by EDM, and investigates the use of a novel surface modification technique, pulsed electron beam irradiation, to improve the most damaging surface property; surface cracking. A transmission electron microscopy (TEM) study was conducted on the surface of single-crystal silicon, which is a chemically and crystallographically homogenous material. For the first time, porosity, contamination and cracking were observed at a scale not visible to conventional imaging techniques such as SEM and optical imaging. The study suggested that conventional microscopic techniques such as SEM and optical microscopy are not sufficient to characterise recast layers created by EDM, and the properties of materials machined by the process are in fact determined by phenomena occurring at the nano-scale. The mechanism behind the movement of material between electrodes was investigated in this thesis. The flushing process in EDM is used to take machined material away from the machining region, and this material is not expected to reattach to electrode surfaces. Using the observation of single discharges and elemental analysis, the mechanism of attachment was determined to be a two-stage process, whereby material ejected at the end of discharge on-time is resolidified in the discharge gap by a successive discharge, which causes its fusion into the opposite electrode surface. This information is critical to the avoidance, or the deliberate deposition of foreign material on a workpiece. Pulsed electron beam irradiation was demonstrated as a rapid and simple method of repairing surface cracks induced by the EDM process. A 4 µm depth of surface cracks created by EDM of stainless steel could be completely eliminated in a pore-free layer. Only a small section of recast layer remained unaffected. The cathode voltage parameter was identified as key to increasing the depth of the remelted layer in future developments of the process. Roughness was at the same time reduced from 3.06 µm to 0.89 µm Sa value. A predominantly austenitic graded nanostructure with grain size down to 6 nm was characterised using TEM and XRD. Such structures have implications for improved mechanical properties via grain boundary strengthening.

In recent years, the use of Oil Palm kernel Shell (OPS) aggregate as coarse aggregate in concrete has received increasing attention due to its environmental and economic benefits. To date, considerable amount of research have been carried out to aid the understanding of its concrete mixture designs and its material properties, but, only limited amount of works have been carried out to aid the current understanding with respect to its shear resistance. The main objective of this research was to investigate the shear resistance of Oil Palm kernel Shell Concrete (OPSC), and to compare with the conventional Normal Weight Concrete (NWC) through experimental and analytical study. The experimental work carried out in this research involved destructive testing of forty-five numbers of beam specimens, of which twenty-nine beams (24 casted with OPSC and 5 casted with NWC) were casted without shear reinforcement while the remaining sixteen beams (11 casted with OPSC and 5 casted with NWC) were casted with shear reinforcement. The main variables for beams casted without shear reinforcement were the concrete strength (fcu), overall section depth (h), longitudinal reinforcement (ρ), and span to depth ratio (a/d). Whilst the main variables for beams casted with shear reinforcement were concrete strength (fcu), shear reinforcement (ρs) and inclination of shear cracks (Θ). For beams casted without shear reinforcement, three distinct failure mechanisms were observed from the tests: the shear compression mechanism (associated with a/d < 2.5); the diagonal tension mechanism (associated with a/d = 2.5 and ρ = 0.88%); and the shear mechanism (associated with a/d ≥ 2.5 and ρ > 0.88%). Whilst for OPSC beams casted with shear reinforcement, shear compression failure was observed for the tests. A comparative study was carried out to investigate if there are any differences on the ultimate shear resistance and the shear failure mechanism between the OPSC beams and NWC beams. In general, all specimens (OPSC and NWC) were found to fail in similar failure mechanism; however, some variations have been noted in the ultimate resistance with respect to span to depth ratio, concrete strength, and longitudinal steel ratio (for beams without shear reinforcement) and concrete strength (for beams with shear reinforcement). An analytical study was carried out using the upper bound approach to evaluate the observed shear failure mechanisms, and hence, to predict the failure loads. A theoretical model was developed for each of the casting condition. In addition, design models based on Eurocode 2 (EC2) and BS8110 have been developed. In all cases, the proposed models achieved good agreement with the test results.